KR101197897B1 - Spindle motor and hard disc drive including the same - Google Patents

Abstract

PURPOSE: A spindle motor and a hard disk drive including the same are provided to easily return the spindle motor in an original location even though a rotating member is inclined to one side. CONSTITUTION: Fixing members(112,130,133) supports rotating members(120,127) by dynamic fluid pressure. An upper radial dynamic pressure groove(114) and a lower radial dynamic pressure groove(115) are formed in one side of the rotating member and the fixing member. A thrust dynamic pressure groove(116) is formed in one side of the rotating member.

Description

SPINDLE MOTOR AND HARD DISC DRIVE INCLUDING THE SAME}

The present invention relates to a spindle motor and a hard disk drive including the same.

A hard disk drive (HDD), which is one of information storage devices, is a device that reproduces data stored on a disk using a read / write head or records data on a disk.

Such a hard disk drive requires a disk drive capable of driving a disk, and a small spindle motor is used for the disk drive.

This compact spindle motor is a fluid dynamic bearing assembly is used, the lubricating fluid is interposed between the shaft which is one of the rotating member and the sleeve of one of the rotating member of the fluid dynamic bearing assembly shaft by the fluid pressure generated from the lubricating fluid Will be supported.

In addition, a rotor hub which rotates together with the shaft and is mounted on the upper side of the shaft and is mounted on the recording disc is mounted, and the rotor hub is fixedly coupled to the upper side of the shaft and has a disk shape that is radially unfolded about the shaft. . The lubricating fluid is also interposed between the upper surface of the sleeve and the rotor hub.

However, in the related art, a thickness standard of a hard disk drive (HDD) corresponds to 9.5 mm for a mobile and 15 mm for a server, and thus a spindle motor mounted thereon may be formed to a certain length in the axial direction. That is, since the bearing span of the upper and lower radial bearings is sufficiently secured, even if the rotating member of the spindle motor is inclined to one side by external force or other force in the process of rotation, the original position is again caused by the fluid dynamic pressure of the upper and lower radial bearings formed between the shaft and the sleeve. There was no difficulty in returning.

However, in recent years, as the size of electronic devices has been miniaturized, the size of hard disk drives used in electronic devices has to be miniaturized to 5 mm or less. Accordingly, the spindle motors used therein are very short in the axial direction.

Accordingly, unlike the conventional spindle motor, since the length of the shaft is shortened, there is a problem that it is difficult to form a fluid dynamic pressure to return to the original position when the rotating member of the spindle motor is inclined to one side. That is, since the bearing span of the upper and lower radial bearings is short, it is difficult to secure sufficient inclination rigidity.

As a method for securing the inclination rigidity by the radial bearing, it is possible to consider increasing the bearing rigidity by generating a fluid dynamic pressure by reducing the bearing gap, that is, the gap between the shaft and the sleeve. However, as dynamic pressure increases, friction loss increases, and ultimately, power consumption increases.

The present invention has been proposed to solve the above problems, and to provide a spindle motor having a sufficient inclination stiffness to easily return to the original position even when the rotating member is inclined to one side in the thin spindle motor.

Spindle motor according to an embodiment of the present invention includes a rotating member and a fixing member for rotatably supporting the rotating member by the fluid dynamic pressure, at least one of the radially opposite surface of the rotating member and the fixing member An upper radial dynamic pressure groove and a lower radial dynamic pressure groove are formed on one surface, and a thrust dynamic pressure groove is formed on at least one of the surfaces facing in the axial direction of the rotating member and the fixing member, and the following Equation 1 may be satisfied. .

[Formula 1]

Where T ₁ is the distance from the center of gravity of the rotating member to the inner end of the thrust dynamic pressure groove, T ₂ is the distance from the center of gravity of the thrust dynamic pressure groove to the outer end of the thrust dynamic pressure groove, α _{1 is the} center of gravity of the rotating member. Smaller angle of the angle between the radial extension line and the line connecting the center of gravity of the rotating member and the inner end of the thrust dynamic pressure groove, α ₂ : The radial extension line passing through the center of gravity of the rotating member is the center of gravity and thrust dynamic pressure groove L _T : The radial length of the thrust dynamic groove, R _U1 : Distance from the center of gravity of the rotating member to the lower end of the upper radial dynamic groove, R _U2 : of the rotating member Distance from center of gravity to upper end of upper radial dynamic groove, β _U1 : Radial extension line passing through center of gravity of rotating member is center of gravity of rotating member And the smaller angle of the angle formed by the line connecting the lower end of the upper radial dynamic groove, β _U2 : The radial extension line passing through the center of gravity of the rotating member forms the line connecting the center of gravity of the rotating member and the upper end of the upper radial dynamic groove. L _U : Axial length of the upper radial hydrodynamic groove, R _L1 : Distance from the center of gravity of the rotating member to the lower end of the lower radial dynamic groove, R _L2 : Lower radial dynamic groove from the center of gravity of the rotating member Distance to the upper end of, _L1 : The smallest angle between the radial extension line passing through the center of gravity of the rotating member and the line connecting the center of gravity of the rotating member to the lower end of the lower radial dynamic groove, β _L2 : of the rotating member The radial extension line passing through the center of gravity is the smaller of the angle formed by the line connecting the center of gravity of the rotating member to the upper end of the lower radial dynamic groove. Angle, L _L : Axial length of lower radial dynamic groove)

In the spindle motor according to an embodiment of the present invention, when the center of gravity of the rotating member is located above the lower end of the upper radial dynamic pressure groove in the axial direction, the term regarding L _U in Equation 1 is 0, The following [Equation 2] can be satisfied.

[Formula 2]

In the spindle motor according to an embodiment of the present invention, when the center of gravity of the rotating member is located axially lower than the upper end of the lower radial dynamic groove, the term regarding L _L in Equation 1 is 0, The following [Equation 3] can be satisfied.

[Equation 3]

In the spindle motor according to an embodiment of the present invention, the rotating member includes a shaft, a hub extending radially outwardly from an upper end of the shaft, and a magnet and a disk mounted to the hub, wherein the fixing member includes the shaft. It may include a sleeve rotatably supported by fluid dynamic pressure, and a coil wound core disposed to face the magnet.

In the spindle motor according to an embodiment of the present invention, the upper and lower radial dynamic pressure grooves are respectively formed on at least one of opposite surfaces of the shaft and the sleeve, and the thrust dynamic pressure grooves are opposite surfaces of the hub and the sleeve. It may be formed on at least one surface.

In the spindle motor according to an embodiment of the present invention, a bearing gap in which fluid is filled is formed between the shaft and an opposite surface of the sleeve, and the bearing gap may be 0.0005 to 0.002 times the diameter of the shaft.

When the power supply is stopped in the spindle motor according to an embodiment of the present invention, the counter electromotive force (B-EMF) may be 0.35V / krpm or more.

A hard disk drive according to an embodiment of the present invention includes a spindle motor; A magnetic head for recording and reproducing data of the disk; And a head conveying part for moving the magnetic head to a predetermined position on the disk, the thickness specification may be 5 mm or less.

Spindle motor according to an embodiment of the present invention includes a rotating member and a fixing member for rotatably supporting the rotating member by the fluid dynamic pressure, at least one of the radially opposite surface of the rotating member and the fixing member An upper radial dynamic pressure groove and a lower radial dynamic pressure groove are formed on one surface, and an upper thrust dynamic pressure groove is formed on at least one surface of an upper side of the rotating member and an axial direction of the fixing member, and a lower side of the rotating member. And a lower thrust dynamic pressure groove is formed on at least one surface of the surfaces facing in the axial direction of the fixing member, and may satisfy Equation 4 below.

[Formula 4]

(T _U1 : distance from the center of gravity of the rotating member to the inner end of the upper thrust dynamic pressure groove, T _U2 : distance from the center of gravity of the rotating member to the outer end of the upper thrust dynamic pressure groove, α _U1 : weight of the rotating member A small angle between the radial extension line passing through the center and the line connecting the center of gravity of the rotating member to the inner end of the upper thrust dynamic groove, α _U2 : The radial extension line passing through the center of gravity of the rotating member L _TU : Radial length of upper thrust dynamic groove, T _L1 : Distance from the center of gravity of the rotating member to the inner end of the lower thrust dynamic groove, T _L2: distance from center of gravity of the rotating member to the lower thrust dynamic pressure outer end of the groove, α _L1: radial passing through the center of gravity of the rotating member Direction extension line of which forms the line connecting the inner end of the center of gravity and the lower thrust dynamic pressure grooves of the rotary member, each small angle, α _L2: the center of gravity of the radial direction extension line passing through the center of gravity of the rotating member the rotating member and the lower thrust dynamic pressure groove L _TL : Radial length of the lower thrust dynamic pressure groove, R _U1 : Distance from the center of gravity of the rotating member to the lower end of the upper radial dynamic groove, R _U2 : Rotating member Distance from the center of gravity of the upper radial dynamic groove to the upper end of the upper radial dynamic groove, β _U1 : The radial extension line passing through the center of gravity of the rotating member is the smaller of the angle between the line connecting the center of gravity of the rotating member and the lower end of the upper radial dynamic groove Angle, β _U2 : The radial extension line passing through the center of gravity of the rotating member is the center of gravity of the rotating member and L _U : Axial length of the upper radial dynamic groove, R _L1 : Distance from the center of gravity of the rotating member to the lower end of the lower radial dynamic groove, R _L2 : of the rotating member Distance from the center of gravity to the upper end of the lower radial dynamic groove, β _L1 : The smaller angle of the radial extension line passing through the center of gravity of the rotating member and the line connecting the center of gravity of the rotating member to the lower end of the lower radial dynamic groove , β _L2 : The smaller angle of the radial extension line passing through the center of gravity of the rotating member to the line connecting the center of gravity of the rotating member to the upper end of the lower radial dynamic groove, L _L : Axial length of the lower radial dynamic pressure groove)

In the spindle motor according to an embodiment of the present invention, when the center of gravity of the rotating member is located axially higher than the lower end of the upper radial dynamic groove, the term about L _U in Equation 4 is 0, The following [Equation 5] can be satisfied.

[Equation 5]

In the spindle motor according to an embodiment of the present invention, when the center of gravity of the rotating member is located axially lower than the upper end of the lower radial dynamic groove, the term regarding L _L in Equation 4 is 0, The following [Equation 6] can be satisfied.

[Equation 6]

In the spindle motor according to an embodiment of the present invention, the rotating member includes a hollow sleeve, a hub extending radially outward of the sleeve, and a magnet and a disk mounted to the hub, wherein the fixing member includes the sleeve. A shaft inserted into the hollow of the shaft to rotatably support the sleeve by fluid dynamic pressure, upper and lower thrust members extending radially outward of the shaft, and a coil wound core corresponding to the magnet. Can be.

In the spindle motor according to an embodiment of the present invention, the upper and lower radial dynamic pressure grooves are formed on at least one of the opposite surfaces of the shaft and the sleeve, respectively, and the upper thrust dynamic pressure grooves are formed of the upper thrust member and the sleeve. The lower thrust dynamic pressure groove may be formed on at least one of opposing surfaces of the lower thrust member and the sleeve.

In the spindle motor according to an embodiment of the present invention, a bearing gap in which fluid is filled is formed between the shaft and an opposite surface of the sleeve, and the bearing gap may be 0.0005 to 0.002 times the diameter of the shaft.

When the power supply is stopped in the spindle motor according to an embodiment of the present invention, the counter electromotive force (B-EMF) may be 0.35V / krpm or more.

A hard disk drive according to an embodiment of the present invention includes a spindle motor; A magnetic head for recording and reproducing data of the disk; And a head conveying part for moving the magnetic head to a predetermined position on the disk, the thickness specification may be 5 mm or less.

The spindle motor according to the present invention may have sufficient inclination stiffness to facilitate the return to the original position even when the rotating member is inclined to one side in the thin spindle motor.

1 is a schematic cross-sectional view showing a spindle motor according to an embodiment of the present invention,
2 is an explanatory view for explaining a mechanism for returning the rotating member inclined to one side in the spindle motor according to an embodiment of the present invention to its original position,
3 and 4 are explanatory diagrams for explaining special cases to which the mechanism described in FIG. 2 may correspond.
FIG. 5 is an explanatory diagram showing definitions of various parameters for mathematically calculating the mechanism described in FIG. 2.
FIG. 6 is an explanatory diagram showing definitions of various parameters for mathematically calculating the mechanism described in FIGS. 2 and 10.
7 and 8 are explanatory diagrams showing a mathematical calculation method of the mechanism described in FIG.
9 is a schematic cross-sectional view showing a spindle motor according to another embodiment of the present invention;
FIG. 10 is an explanatory diagram showing definitions of various parameters for applying the mechanism illustrated in FIG. 2 to the spindle motor according to the embodiment shown in FIG. 9;
FIG. 11 is an explanatory diagram showing definitions of various parameters for mathematically calculating the mechanism described in FIG. 10.
12A and 12B are schematic cross-sectional views of a disk drive apparatus using a spindle motor according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventive concept. Other embodiments which fall within the scope of the inventive concept may be easily suggested, but are also included within the scope of the present invention.

In addition, in describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a schematic cross-sectional view showing a spindle motor according to an embodiment of the present invention.

1, a spindle motor 100 according to an embodiment of the present invention includes a hydrodynamic bearing assembly 110 including a shaft 111, a rotor 120, and a sleeve 112, a hub 121, The base member 133 and the stator 130 including the core 131 in which the coil 132 is wound.

1, the axial direction refers to a vertical direction with respect to the shaft 111, and a radially outer and an inner direction refer to the direction of the shaft 111 with respect to the shaft 111, The center of the shaft 111 may be referred to as an outer end of the shaft 121 and an outer end of the hub 121. [ Also, the circumferential direction may mean a direction of rotation about the rotation axis at a position spaced a predetermined distance in the radial direction about the rotation axis.

In the following description, the rotating member is a rotating member including a shaft 111, a rotor 120 including a hub 121, a magnet 127 mounted thereon, and the like. Such as the sleeve 112, the stator 130, and the base member 133, which are relatively fixed to the rotating member.

The hydrodynamic bearing assembly 110 may include a shaft 111, a sleeve 112, a stopper 111a, and a hub 121, and the hub 121 may be a component constituting the rotor 120 to be described later. At the same time, the fluid dynamic bearing assembly 110 may be configured to constitute.

The sleeve 112 may rotatably support the shaft 111.

Here, the shaft 111 is inserted to have a small gap with the shaft hole of the sleeve 112 to form a bearing gap (C). The shaft 111 may be provided with a diameter of 4mm or less. The bearing gap may be filled with oil. The bearing gap C may be formed to be 0.0005 to 0.002 times the diameter D of the shaft 111. That is, a value obtained by dividing the bearing gap C by the diameter D of the shaft may be 0.0005 to 0.002. If the bearing clearance is smaller than this, the bearing stiffness can be increased, but there is a problem in that the power consumption is increased due to a large friction loss. In addition, if the bearing clearance is made larger than this, friction loss can be reduced, but bearing rigidity cannot be secured. The numerical range of such shaft diameters and bearing clearances is described in US Pat. No. 5,647,672.

Upper and lower radial dynamic pressure grooves 114 and 115 may be formed on at least one of the outer diameter of the shaft 111 and the inner diameter of the sleeve 112. The upper and lower radial dynamic pressure grooves 114 and 115 generate fluid dynamic pressure in the radial direction when the shaft 111 rotates to form a radial dynamic pressure bearing thereby smoothly rotating the rotor 120 Can support.

The upper and lower radial dynamic pressure grooves 114 and 115 are formed in a plurality of circumferential directions and may be any one of a herringbone shape, a spiral shape, and a threaded shape.

The sleeve 112 may include a circulation hole formed to communicate between the upper portion and the lower portion of the sleeve 112. The circulation holes can maintain the equilibrium of pressure generated in the upper and lower radial dynamic pressure grooves 114 and 115, and the bubbles or the like existing in the fluid dynamic pressure bearing assembly 110 can be discharged by circulation .

Here, a stopper 111a protruding outward in the radial direction may be provided at the lower end of the shaft 111. [ The stopper 111a may be engaged with the lower end surface of the sleeve 112 to limit the lifting of the shaft 111 and the rotor 120.

In addition, the cover member 113 is coupled to the lower axial direction of the sleeve 112 to cover the shaft hole to prevent the leakage of oil (lubricating fluid) may be provided.

Since the hub 121 is coupled to the shaft 111 and constituting the fluid dynamic bearing assembly 110 with a rotating member that rotates in association with the shaft 111, the rotor 120 may be configured as follows. The rotor 120 will be described in detail.

The rotor 120 is a rotating structure rotatably provided with respect to the stator 130. The rotor 120 may include a hub 121 having a ring-shaped magnet 127 on its inner circumferential surface corresponding to the core 131 at a predetermined interval.

In other words, the hub 121 is a rotating member that is coupled to the upper end of the shaft 111 and rotates in conjunction with the shaft 111.

Here, the magnet 127 may be provided as a permanent magnet that alternately magnetizes N and S poles in a circumferential direction to generate a magnetic force of a predetermined intensity.

In addition, the hub 121 is a first cylindrical wall portion 122 to be fixed to the upper end of the shaft 111, a disc portion 123 extending radially outward from the end of the first cylindrical wall portion 122, It may include a second cylindrical wall portion 124 protruding downward from the radially outer end of the disc portion 123, the magnet 127 may be coupled to the inner peripheral surface of the second cylindrical wall portion 124. In addition, the hub 121 may include a disk mounting portion 125 protruding radially outward from a lower end of the second cylindrical wall portion 124.

The hub 121 may include a main wall portion 126 extending downward in the axial direction so as to correspond to an upper outer portion of the sleeve 112. In more detail, it may be provided with a main wall portion 126 which extends downward from the disc portion 123 in the axial direction. A gas-liquid interface sealing the oil may be formed between the outer side of the sleeve 112 and the inner side of the circumferential wall 126.

In addition, the inner surface of the circumferential wall 126 is tapered so that the gap between the outer surface of the sleeve 112 and the outer circumferential surface of the sleeve 112 becomes wider toward the lower axial direction, thereby facilitating sealing of the oil. The outer surface of the sleeve 112 may be tapered.

Further, the outer surface of the circumferential wall 126 may be formed to correspond to the upper portion 136 of the mounting portion 134 protruding upward from the base member 133.

A thrust dynamic pressure groove 116 may be formed at a portion where the hub 121 and the sleeve 112 face each other. The thrust dynamic pressure groove 116 may be formed in plural in a circumferential direction, and may be provided in a spiral, herringbone, and spiral shape, and there is no limitation in shape as long as it has a structure capable of generating dynamic pressure.

The thrust dynamic pressure groove 116 generates thrust fluid dynamic pressure when the shaft 111 rotates relative to the sleeve 112 to form a thrust dynamic pressure bearing between the hub 121 and the sleeve 112 .

Meanwhile, in the related art, when the rotating member is inclined to one side, the rotating member may be returned to its original position by the fluid dynamic pressure of the upper and lower radial bearings formed between the shaft and the sleeve. However, in recent years, according to the trend of thinning of hard disk drives (HDD), the spindle motor mounted thereon is also made thin (HDD standard 5mm or less).

Accordingly, in the thinned spindle motor, the length of the shaft is shortened, making it difficult to secure the span of the upper and lower radial bearings. Therefore, when the rotating member is inclined to one side, it may be difficult to form sufficient fluid dynamic pressure to return the inclined rotating member to its original position. In order to secure the stiffness of the radial bearing, the bearing clearance can be reduced to generate the fluid dynamic pressure so that the bearing stiffness can be increased. However, it is not preferable because the dynamic loss increases the friction loss and ultimately the power consumption. .

Therefore, the spindle motor according to an embodiment of the present invention is designed to improve the problem of the inclination rigidity of the weak radial bearing, and the load of the inclination rigidity is increased in the radial bearing rather than the inclination rigidity of the radial bearing itself. And a structure in which the inclined rotating member can be returned to its original position by the fluid dynamic pressure formed between the thrust member and the sleeve. This will be described later.

On the other hand, in one embodiment of the present invention, the thrust member may be any member as long as it is fixed to the shaft and generates a thrust fluid dynamic pressure between the sleeve and which rotates relatively. For example, the hub 121 coupled to the shaft 111 in FIG. 1 generates a thrust fluid dynamic pressure between the sleeve 112 and the hub 121, so that the hub 121 is a thrust member. That is, it can be a thrust member according to the role without restricting a name.

The stator 130 may include a core 131, a coil 132, and a base member 133.

In other words, the stator 130 may be a fixing member having a coil 132 generating an electromagnetic force of a predetermined magnitude when power is applied and a plurality of cores 131 through which the coil 132 is wound.

The core 131 is fixedly disposed on an upper portion of a base member 133 having a printed circuit board (not shown) on which a pattern circuit is printed, and the base member 133 is fixed to the base member 133 such that the coil 132 is exposed downward A coil hole having a predetermined size can be formed through the through hole. The coil 132 may be electrically connected to the printed circuit board (not shown) to receive external power.

In addition, the fluid dynamic pressure bearing assembly 110 may be mounted on the base member 133. The base member 133 can be manufactured by a die casting method using aluminum (Al) as a material, and can be manufactured by a method in which a steel sheet is subjected to plastic working (e.g., press working).

The base member 133 may include a mounting part 134 protruding upward in the axial direction. The core 131 may be mounted on an outer side surface of the mounting unit 134, and the sleeve 112 may be fitted and fixed to an inner side surface thereof. In addition, the upper portion 136 of the inner surface of the mounting portion 134 may be formed so that the outer surface of the main wall portion 126 to face. Between the circumferential wall portion 126 and the upper portion 136 of the mounting portion 134 facing each other may be formed at a sufficiently narrow interval to form a labyrinth seal (Labyrinth seal).

FIG. 2 is an explanatory view for explaining a mechanism for returning a rotating member inclined to one side to a home position in a spindle motor according to an embodiment of the present invention, and FIGS. 3 and 4 mathematically calculate the mechanism described in FIG. 5 and 6 are explanatory diagrams showing a mathematical calculation method of the mechanism described in FIG. 2, and FIGS. 7 and 8 may correspond to the mechanisms described in FIG. 2. An explanatory diagram illustrating a special case.

Referring to FIG. 2, in the spindle motor 100 according to an exemplary embodiment of the present invention, when the rotating member rotates relative to the fixing member, the rotating member may be inclined to one side by an external impact or other force. That is, the shaft 111 rotatably mounted to the sleeve 112 may be inclined to one side. When the shaft 111 is inclined, the hub 121 mounted on the shaft 111 is also inclined to one side.

In the case where the shaft 111 is not inclined to the sleeve 112, a bearing gap formed by the shaft 111, the sleeve 112, the sleeve 112, and the hub 121, respectively. This constant interval is maintained. Therefore, the rotating member may be rotated relative to the fixing member in a state in which a constant fluid dynamic pressure is formed between the shaft 111 and the sleeve 112 and the sleeve 112 and the hub 121, respectively, in a balanced state.

However, when the rotating member is inclined, the bearing gap does not maintain a constant gap.

That is, as shown in FIG. 2, in the case of a solid line in which the rotating members (shaft 111 and the hub 121) are not inclined, the rotating member (in contrast to the bearing 112 maintains a constant distance between the sleeve 112 and the rotating member ( In the case where the shaft 111 and the hub 121 are inclined dotted lines, the bearing clearance varies between the sleeve 112 and the position.

In this case, if the spindle motor has a long length in the axial direction (motor used for HDD thickness standard 9.5mm or 15mm), it is difficult to return to the original position by the fluid dynamic pressure of the upper and lower radial bearings formed between the shaft and the sleeve. There was no. However, if the spindle motor has a relatively short length in the axial direction (a motor used for the HDD thickness specification of 5 mm or less), it may be difficult to return to the original position by the fluid dynamic pressure of the upper and lower radial bearings formed between the shaft and the sleeve. have.

Thus, referring to FIG. 2, when the shaft 111 is inclined to one side, a portion in which the bearing gap of the portion in which the dynamic pressure groove is formed is further narrowed is formed (S _T , S _U , and S _L in FIG. 2). In this part, the fluid dynamic pressure formed between the members can be made larger as the bearing clearance becomes narrower. That is, the portion in which the dynamic pressure groove is formed may have a larger fluid dynamic pressure in proportion to the area where the gap between the members facing each other becomes closer. Thus, in one embodiment of the present invention, this principle can be used to mathematically establish the position and size relationship of the thrust dynamic groove 116 and the radial dynamic groove 114, 115.

When the rotating member (the shaft 111 shown in FIG. 2) is inclined to one side, the fluid dynamic pressure to return the rotating member to the opposite side of the one side is further generated as the rotating member is inclined to one side. The fluid dynamic pressure can be understood. That is, the distance difference between the members facing each other in the portion where the dynamic pressure groove is formed may be close. This is the area (S _T , S _{U) of the} portion where the gap between the shaft 111 and the hub 121 is inclined and after being inclined in the portion where the dynamic groove is formed in FIG. 2. And S _L ).

That is, the area S _T according to the gap difference between the inclination of the hub 121 and the inclination of the hub 121 in the thrust dynamic groove 116 is formed at the portion where the radial dynamic grooves 114 and 115 are formed. 111 may be larger than the area (S _U + S _L ) according to the gap difference before and after the inclination. As a result, Equation 1 below can be established.

[Equation 1]

By designing to satisfy the above formula, the thrust bearing bears more inclination rigidity than the radial bearing.

That is, in the thin structure, the inclination rigidity due to the radial bearing becomes weak, but the inclination rigidity due to the thrust bearing is improved, so that when the rotating member is inclined, the thrust bearing resists the inclination, thereby preventing tilting.

On the other hand, in the case of the double thrust structure in which the thrust member is formed up and down, respectively, the area S _T according to the gap difference before and after the inclination of the thrust member is inclined at the portion where the thrust dynamic pressure groove is formed, the thrust is formed up and down respectively. In the part in which the thrust dynamic pressure groove is formed, the upper and lower thrust members may be the sum of the areas according to the gaps before and after the inclination.

On the other hand, in one embodiment of the present invention, the thrust member may be any member as long as it is fixed to the shaft and generates a thrust fluid dynamic pressure between the sleeve and which rotates relatively. For example, the hub 121 coupled to the shaft 111 in FIG. 1 generates a thrust fluid dynamic pressure between the sleeve 112 and the hub 121, so that the hub 121 is a thrust member. That is, it can be a thrust member according to the role without restricting a name.

5 to 8, parameters and mathematical arithmetic methods for solving and arranging [Equation 1] are presented.

Referring to FIGS. 5 and 6, each parameter is defined as follows.

T ₁ : distance from the center of gravity of the rotating member to the inner end of the thrust dynamic pressure groove, T ₂ : distance from the center of gravity of the thrust dynamic groove to the outer end of the thrust dynamic pressure groove, α ₁ : radial direction passing through the center of gravity of the rotating member The smaller angle of the extension line is formed between the line connecting the center of gravity of the rotating member and the inner end of the thrust dynamic pressure groove, α ₂ : The radial extension line passing through the center of gravity of the rotating member is the center of gravity of the rotating member and the outer end of the thrust dynamic groove. L _T : Radial length of thrust dynamic groove, R _U1 : Distance from the center of gravity of the rotating member to the lower end of the upper radial dynamic groove, R _U2 : At the center of gravity of the rotating member the center of gravity and the upper portion of the radial direction extension line passing through the center of gravity of the rotating member the rotating member: the distance to the upper radial dynamic pressure upper end of the groove, β _U1 Forming the line connecting the lower end a small angle of each of the radial dynamic pressure groove, β _U2: of the forming line and to the radial direction extension line passing through the center of gravity of the rotating member connected to the center of gravity and the upper end of the upper radial dynamic pressure grooves of the rotary members each Small angle, L _U : Axial length of the upper radial hydrodynamic groove, R _L1 : Distance from the center of gravity of the rotating member to the lower end of the lower radial dynamic groove, R _L2 : Upper side of the lower radial dynamic groove at the center of gravity of the rotating member Distance to the end, β _L1 : The smallest angle between the radial extension line passing through the center of gravity of the rotating member and the line connecting the lower end of the lower radial dynamic pressure groove with the center of gravity of the rotating member, β _L2 : Center of gravity of the rotating member a through radial extension forming a smaller angle of each line connecting the center of gravity and the lower radial dynamic pressure grooves of the upper end of the rotating member, L _L: It means the axial length of the radial dynamic pressure groove portion.

In addition, in one embodiment of the present invention, the center of gravity G of the rotating member means a final state in which a disk, a clamp, or the like is mounted on the spindle motor. The spindle motor 100 shown in FIG. 1 is in a state where a disk, a clamp, or the like is not mounted, and the center of gravity G shown in FIGS. 2 to 8 means a center of gravity of a rotating member on which a disk, a clamp, or the like is mounted. do.

Next, when the rotating member is inclined to one side with reference to FIGS. 7 and 8, the change amount of the bearing gap, that is, the bearing gap change amount ΔY of the portion where the thrust fluid dynamic pressure is formed, and the bearing of the radial fluid dynamic pressure is formed. A method of calculating the gap change amount ΔX will be described.

The bearing gap change amount ΔY of the portion where the thrust fluid dynamic pressure is formed is the inclined rotary member facing the axial position of the pre-inclined rotating member facing one end of the thrust dynamic pressure groove 116 and the one end of the thrust dynamic pressure groove 116. Means the difference in the axial position. Therefore, it can be estimated by ΔY = Y ₁ -Y ₂ in the illustration of FIG. Solving this in detail, it can be calculated as shown in [Equation 2] below.

&Quot; (2) "

Where T is the distance from the center of gravity of the rotating member to one end of the thrust dynamic pressure groove (exactly the distance from the center of gravity of the rotating member to the point of the rotating member facing one end of the thrust dynamic pressure groove, but the value is Almost the same), α: the small angle of the radial extension line passing through the center of gravity of the rotating member and the line connecting one end of the thrust dynamic groove with the center of gravity of the rotating member (exactly, passing through the center of gravity of the rotating member The radial extension line is an angle formed by a line connecting the center of gravity of the rotating member and the point of the rotating member facing one end of the thrust dynamic pressure groove, but the value thereof is almost the same), θ: inclination angle of the rotating member (wherein θ Is a small angle, so we can assume that sinθ = θ and cosθ = 1))

The bearing gap change amount ΔX of the portion where the radial fluid dynamic pressure is formed may be calculated by Equation 3 below.

The bearing gap change amount ΔX of the portion where the radial fluid dynamic pressure is formed is a radial member of the pre-inclined rotating member facing one end of the radial dynamic pressure groove 114 and the inclined rotating member facing one end of the radial dynamic pressure groove 114. Means the difference in radial position. Therefore, it can be estimated by ΔX = X ₁ -X ₂ in the illustration of FIG. 6. Solving this in detail, it can be calculated as shown in Equation 3 below.

&Quot; (3) "

Where R is the distance from the center of gravity of the rotating member to one end of the radial dynamic groove (exactly the distance from the center of gravity of the rotating member to the point of the rotating member facing one end of the radial dynamic groove, but the value is Approximately the same), β: the small angle of the radial extension line passing through the center of gravity of the rotating member and the line connecting one end of the radial dynamic pressure groove (exactly, the center of gravity of the rotating member The radial extension line is the angle formed by the line connecting the center of gravity of the rotating member and the point of the rotating member facing one end of the radial dynamic groove, but the value is almost the same), θ: The inclination angle of the rotating member (where θ is Since it is a small angle, we can assume that sinθ = θ and cosθ = 1))

Again, referring to FIG. 2, the area for each item may be calculated to calculate Equation 1 above.

Since the area S _T according to the gap difference between the inclination of the hub 121 and the inclination at the portion where the thrust dynamic pressure groove 116 is formed may be calculated by a formula for obtaining the area of the trapezoid, the following equation 4].

&Quot; (4) "

(Where, ΔY ₁ : change amount of the bearing gap in the portion where the inner end of the thrust dynamic pressure groove is located, ΔY ₂ : change amount of the bearing gap in the portion where the outer end of the thrust dynamic pressure groove is located, and the remaining parameters are described in the above FIGS. 5 to 8) See)

Next, the area S _U according to the gap difference before and after the inclination of the shaft 111 at the portion where the upper radial dynamic groove 114 is formed may be calculated by a formula for obtaining the area of the trapezoid, It can be calculated by Equation 5 below.

[Equation 5]

(Where, ΔX _U1 : change amount of bearing gap in the position where the lower end of the upper radial dynamic groove is located, ΔX _U2 : change amount of bearing gap in the position where the upper end of the upper radial dynamic groove is located, and the remaining parameters are shown in FIGS. 5 to 8. See description in)

In addition, since the area S _L according to the gap difference before and after the inclination of the shaft 111 at the portion where the lower radial dynamic groove 115 is formed may be calculated by a formula for obtaining the area of the trapezoid, It can be calculated by Equation 6.

&Quot; (6) "

(Where, ΔX _L1 : change amount of bearing gap in the portion where the lower end of the lower radial dynamic groove is located, ΔX _L2 : change amount of bearing gap in the portion where the upper end of the lower radial dynamic groove is located, and the remaining parameters are shown in FIGS. 5 to 8. See description in)

Therefore, substituting [Equation 4] to [Equation 6] into [Equation 1] is the same as [Equation 7], and sums it up to [Equation 8].

[Equation 7]

[Equation 8]

Therefore, when the thrust dynamic pressure groove and the radial dynamic pressure groove establish the relationship of the above [Equation 8], the thrust bearing than the radial bearing resists the inclination, so that tilting can be prevented.

On the other hand, the center of gravity of the rotating member may be formed at various locations according to the structure and shape of the rotating member. In particular, in the case of the spindle motor according to an embodiment of the present invention, if the center of gravity of the rotating member is formed in the upper radial dynamic groove or the lower radial dynamic groove region, the relationship between the thrust dynamic groove and the radial dynamic groove is simply established. Can be.

Referring to Figure 3, the center of gravity (G) of the rotating member may be located in the upper radial dynamic pressure groove region and its upper region. Also in this case, the thrust dynamic pressure groove and the radial dynamic pressure groove should satisfy the relationship of Equation 1 above.

By the way, when the center of gravity (G) of the rotating member is located in the upper radial dynamic pressure groove area and the upper area thereof, the shaft 111 at the portion where the upper radial dynamic pressure groove 114 is formed among the items of Equation 1 above. The area (S _U ) according to the difference between the gaps before and after the inclination becomes negligibly small. Therefore, Equation 1 may be simplified to Equation 10 below.

&Quot; (10) "

Therefore, substituting [Equation 4] and [Equation 6] into the above [Equation 10] is the same as [Equation 11], when summed up [Equation 12] is derived.

&Quot; (11) "

[Equation 12]

In addition, referring to Figure 4, the center of gravity (G) of the rotating member may be located in the lower radial dynamic pressure groove region and its lower region. Also in this case, the thrust dynamic pressure groove and the radial dynamic pressure groove should satisfy the relationship of Equation 1 above.

By the way, when the center of gravity (G) of the rotating member is located in the lower radial dynamic pressure groove area and the lower area thereof, the shaft 111 at the portion where the lower radial dynamic pressure groove 115 is formed among the items of Equation 1 above. The area S _L according to the difference between the gaps before and after the inclination is negligibly small. Therefore, Equation 1 may be simplified to Equation 13 below.

&Quot; (13) "

Therefore, substituting [Equation 4] and [Equation 5] into [Equation 13] is the same as [Equation 14], and sums it up to [Equation 15].

&Quot; (14) "

&Quot; (15) "

Therefore, when the center of gravity G of the rotating member is located within the area of the radial dynamic groove, the thrust dynamic groove and the radial dynamic groove may satisfy the following Equation 12 or Equation 15.

In the embodiment of Figures 1 to 8, the hub has been described centering on the axial rotational structure in which the rotation is coupled to the shaft, it is, of course, also applicable to the shaft fixed structure in which the hub is rotated by coupling to the sleeve.

9 is a schematic cross-sectional view showing a spindle motor according to another embodiment of the present invention, and FIG. 10 shows the definition of various parameters for applying the spindle motor according to the embodiment shown in FIG. It is explanatory drawing.

Referring to FIG. 9, the spindle motor 200 according to another embodiment of the present invention may include a base member 210, a lower thrust member 220, a shaft 230, a sleeve 240, a hub 250, and an upper thrust. It may be configured to include a member 260 and a cap member 290.

First, the term for the direction is defined, and in the axial direction as shown in FIG. 9, the radial direction means a lateral direction, ie, a direction from the shaft 230 toward the outer circumferential surface of the hub 250 or a direction from the outer circumferential surface of the hub 250 toward the shaft 230, and is circumferential. The direction means the direction of rotation along a predetermined radius at the center of rotation. For example, it may mean a direction that is rotated along the outer circumferential surface of the hub 150.

The spindle motor 200 according to the embodiment of the present invention allows the rotating member to smoothly rotate relative to the holding member using the fluid dynamic pressure bearing assembly.

The fluid dynamic pressure bearing assembly is composed of members rotating relative to each other by generating fluid dynamic pressure through a lubricating fluid. The lower thrust member 220, the sleeve 240, the shaft 230, the upper thrust member 260, And a hub 250.

The rotating member may include a sleeve 240 and a hub 250 and may include a magnet 284 provided on the hub 250. The rotating member may be a relatively rotating member.

Furthermore, the fixing member is a member fixed relatively to the rotating member, and may include a base member 210, a shaft 230, a lower thrust member 240, and an upper thrust member 260.

The base member 210 may have a mounting groove 212 to form a predetermined space together with the hub 250. The base member 210 may include a coupling portion 214 that extends toward the upper side in the axial direction and has a stator core 202 at an outer circumferential surface thereof.

In addition, the seating surface 214a may be provided on the outer circumferential surface of the coupling portion 214 so that the stator core 202 can be seated and installed. The stator core 202 mounted on the coupling portion 214 may be disposed above the mounting groove 212 of the base member 210 described above.

Meanwhile, the base member 210 according to the present embodiment can be manufactured by plastic working of a rolled steel sheet. In more detail, the base member 210 may be manufactured by pressing, stamping, deep drawing, or the like. However, the production of the base member 210 is not limited to this, and the base member 210 may be manufactured by various methods not illustrated, such as aluminum die casting.

On the other hand, since the base member 210 is manufactured by the plastic working of the rolled steel sheet, the thickness of the base member 210 is made thin and uniform. Therefore, it may not be easy to integrally form the coupling part 214 provided in the base member 210. Accordingly, in the case of the base member 210 according to an embodiment, the coupling part 214 may be manufactured as a separate member and coupled to the base member 210 when the spindle motor is assembled.

The lower thrust member 220 is fixed to the base member 210. That is, the lower thrust member 220 is inserted into the engaging portion 214, and more specifically, the outer circumferential surface of the lower thrust member 220 may be attached to the inner circumferential surface of the engaging portion 214.

The lower thrust member 220 includes a disc portion 222 whose inner surface is fixed to the shaft 230 and whose outer surface is fixed to the base member 210 and a disc portion 222 extending upward from the disc portion 222 in the axial direction And may have an extension portion 224 formed therein.

That is, the lower thrust member 220 may have a cup shape having a hollow shape. That is, the cross section may be formed to have a '' 'shape.

In addition, the disc portion 222 may be provided with a mounting hole 222a for mounting the shaft 230, and the shaft 230 is inserted into the mounting hole 222a.

The lower thrust member 220 is included in the fixing member, that is, the stator together with the base member 210.

On the other hand, the outer surface of the lower thrust member 220 may be bonded to the inner surface of the base member 210 by an adhesive agent and / or by welding. In other words, the outer surface of the lower thrust member 220 is fixedly bonded to the inner surface of the engaging portion 214 of the base member 210.

At least one of the upper surface of the lower thrust member 220 or the lower surface 240b of the sleeve 240 may be formed with a lower thrust dynamic pressure groove 249 for generating thrust fluid dynamic pressure. In FIG. 9, the lower thrust dynamic pressure groove 249 is formed on the lower surface of the sleeve 240, but the present invention is not limited thereto. 220 may be provided.

In addition, the lower thrust member 220 may simultaneously serve as a sealing member to prevent leakage of the lubricating fluid.

The shaft 230 is fixed to at least one of the lower thrust member 220 and the base member 210. That is, the lower end of the shaft 230 may be installed to be inserted into the mounting hole 222a formed in the disc portion 222 of the lower thrust member 220.

In addition, the lower end of the shaft 230 may be joined to the inner surface of the disc portion 222 by an adhesive agent and / or by welding. Accordingly, the shaft 230 can be fixed.

However, the present invention is not limited to this, and the shaft 230 may be fixed to the base member 210, It might be.

Meanwhile, the shaft 230 is also included in the fixing member, that is, the stator, together with the lower thrust member 220 and the base member 210.

An upper surface of the shaft 230 may be provided with a coupling means, for example, a screw portion to which a screw is fastened so that a cover member (not shown) may be fixedly installed.

The sleeve 240 may be rotatably mounted on the shaft 230. To this end, the sleeve 240 may have a through hole 241 through which the shaft 230 is inserted. When the sleeve 240 is installed on the shaft 230, the inner circumferential surface of the sleeve 240 and the outer circumferential surface of the shaft 230 are spaced apart from each other by a predetermined distance to form a bearing gap B. The bearing gap B is then filled with a lubricating fluid.

On the other hand, a stepped surface 244 for forming a labyrinth-shaped sealing portion between the upper thrust member 260 and the upper thrust member 260 may be formed at the upper end of the sleeve 240. Sealing of the lubricant can be firmly performed by the labyrinth-shaped sealing portion formed by the stepped surface 244 and the upper thrust member 260.

On the outer surface of the upper end of the upper thrust member 260, an inclined portion 263 having an upper side outer diameter larger than the lower side outer diameter so as to form a first gas-liquid interface F1 with the hub 250 .

In other words, an upper end portion of the upper thrust member 260 is formed with an upper outer diameter at an outer diameter of the lower side so that a first gas-liquid interface F1 can be formed in a space between the outer circumferential surface of the upper thrust member 260 and the inner circumferential surface of the hub 250 An inclined portion 263 that is formed to be larger can be formed.

A hub 250 is joined to the outer circumferential surface of the sleeve 240. That is, the lower portion of the stepped surface 244 may have a shape corresponding to the inner surface of the hub 250, so that the hub 250 may be fixedly installed. That is, the outer circumferential surface of the sleeve 240 may have a joint surface.

Here, the sleeve 240 and the hub 250 may be integrally formed. In the case where the sleeve 240 and the hub 250 are integrally formed, the sleeve 240 and the hub 250 are all provided as one member, so that the number of parts is reduced and the assembly of the product is easy and the assembly tolerance can be minimized .

The lower end of the outer circumferential surface of the sleeve 240 may be formed with an upward inclination toward the radially inward direction so as to form a gas-liquid interface with the extended portion 224 of the lower thrust member 220.

That is, the lower end of the sleeve 240 is inclined upward toward the radially inward direction so that the second gas-liquid interface F2 can be formed in the space between the outer circumferential surface of the sleeve 240 and the extended portion 224 of the lower thrust member 220 . That is, the sealing portion of the lubricant may be formed in a space between the outer circumferential surface of the sleeve 240 and the extending portion 224 of the lower thrust member 220.

As described above, since the second gas-liquid interface F2 is formed in the space between the lower end of the sleeve 240 and the extending portion 224, the lubricant filled in the bearing gap B has the first gas-liquid interface F1 and the second gas- Liquid interface F2 is formed.

The inner surface of the sleeve 240 is provided with upper and lower radial dynamic pressure grooves 248 and 249 for generating fluid dynamic pressure through a lubricant filled in the bearing gap B during rotation of the sleeve 240 .

However, the upper and lower radial dynamic grooves 248 and 249 are not limited to those formed on the inner surface of the sleeve 240 as shown in FIG. 9, and may be formed on the outer circumferential surface of the shaft 230. It may be provided in a variety of shapes, such as herringbone, spiral, screw.

The hub 250 is coupled to the sleeve 240 and rotates in conjunction with the sleeve 240.

The hub 250 includes a hub body 252 having an insertion portion into which the upper thrust member 260 is inserted, and a mounting portion extending from an edge of the hub body 252 to mount the magnet assembly 280 on an inner surface thereof. 254 and an extension 256 extending radially outward from the end of the mounting portion 254.

The lower end of the inner surface of the hub body 252 may be joined to the outer surface of the sleeve 240. That is, the lower end of the inner surface of the hub body 252 may be bonded to the bonding surface 245 of the sleeve 240 by an adhesive and / or by welding.

Accordingly, the sleeve 240 can be rotated together with the hub 250 when the hub 250 rotates.

In addition, the mounting portion 254 extends downward from the hub body 252 in the axial direction. In addition, the magnet assembly 280 may be fixedly installed on the inner surface of the mounting portion 254.

The magnet assembly 280 may include a yoke 282 fixed to the inner surface of the mounting portion 254 and a magnet 284 disposed on the inner circumferential surface of the yoke 282.

The magnet 284 may have a ring-like shape and may be a permanent magnet that alternately magnetizes N and S poles along the circumferential direction to generate a magnetic field having a constant intensity.

On the other hand, the magnet 284 is disposed opposite to the tip of the stator core 202, the coil 201 is wound, the hub 250 by the electromagnetic interaction with the stator core 202 wound the coil 201 Generate a driving force to be able to rotate.

The upper thrust member 260 is fixed to the upper end of the shaft 230 and forms a gas-liquid interface with the sleeve 240 or the hub 250.

The upper thrust member 260 includes a body 262 having an inner surface bonded to the shaft 230 and a protrusion 264 extending from the body 262 to form a gas-liquid interface with the inclined portion 243 .

The protrusion 264 extends axially downward from the body 262 and has an inner surface facing the outer surface of the sleeve 240 and an outer surface facing the inner surface of the hub 250.

Also, the protrusion 264 may extend from the body 262 in parallel with the shaft 230.

The upper thrust member 260 is also a stationary member fixedly installed together with the base member 210, the lower thrust member 220, and the shaft 230, and constitutes a stator.

Since the upper thrust member 260 is fixed to the shaft 230 and the sleeve 240 is rotated together with the hub 250, a space between the hub 250 and the protrusion 264 is filled with the first gas-liquid interface F1 May be formed. The inner surface of the hub 250 may have an inclined portion 253 that is inclined.

However, the protrusion 264 of the upper thrust member 260 is disposed in a space between the sleeve 240 and the hub 250. The lower surface of the body 262 of the sleeve 240 and the upper thrust member 260 includes an outer surface of the sleeve 240 and an inner surface of the protrusion 264 and an outer surface of the protrusion 264, 250 are filled with a lubricant in the shape of a maze (labyrinth) along the space formed by the inner surfaces of the respective inner surfaces of the outer and inner surfaces.

Therefore, the first gas-liquid interface F1 may be formed in the space formed by the outer surface of the upper thrust member 260 and the inner surface of the hub 250 as shown in FIG. It may be formed on the outer surface of the 240 and the inner surface of the protrusion 264. Of course, in the latter case, the outer surface of the sleeve 240 or the inner surface of the protrusion 264 may be inclined to facilitate sealing of the lubricant.

An upper thrust dynamic pressure groove 248 for generating a thrust dynamic pressure may be formed on at least one of the bottom surface of the upper thrust member 260 or the upper surface of the sleeve 240 disposed opposite the lower surface of the upper thrust member 260 have.

The upper thrust member 260 may also function as a sealing member for preventing the lubricant, which is filled in the bearing gap B, from leaking to the upper side.

The cap member 290 covers the space formed by the upper thrust member 260 and the hub 250 from above.

The cap member 290 may be provided in a ring shape, and an outer end thereof may be fixed to the inner side of the hub 250.

FIG. 10 is an explanatory diagram showing definitions of various parameters for applying the mechanism illustrated in FIG. 2 to the spindle motor according to the embodiment shown in FIG. 9, and FIG. 11 is a diagram for mathematically calculating the mechanism described in FIG. 10. An explanatory diagram showing the definition of various parameters.

Referring to FIG. 10, there is a difference in that a double thrust structure having two thrust bearings is compared with the embodiment of FIG. 2 which is a single thrust structure. Therefore, when the sleeve 240, which is a rotating member, is inclined, a force that resists the inclination in the upper and lower thrust bearings is generated. That is, what is represented by Equation 1 in the embodiment of FIG. 2 may be represented by Equation 16 in the embodiment of FIG. 10.

&Quot; (16) "

Equation 16 is applied to the double thrust structure, except that the fluid dynamic pressure S _TL acting between the sleeve 240 and the lower thrust member 220 is added to Equation 1, FIGS. The principle applied when the rotating member of the spindle motor 100 is inclined according to an embodiment of the present invention described with reference to FIG. 8 may be applied as it is.

10 and 11, a parameter and a mathematical arithmetic method for solving and arranging Equation 16 will be described.

Referring to FIGS. 10 and 11, each parameter is defined as follows. However, the spindle motor 200 according to the present embodiment has a difference only in that the shaft is fixed shaft structure and provided with a double thrust structure, compared to the one shown in Figure 1, [Equation 1] to [mathematical formula] The principle applied to Equation 15 is the same. Therefore, the same symbol is used for a parameter having the same meaning, and the added parameter will be described in detail.

T _U1 : Distance from the center of gravity of the rotating member to the inner end of the upper thrust dynamic pressure groove, T _U2 : Distance from the center of gravity of the upper thrust dynamic pressure groove to the outer end of the upper thrust dynamic pressure groove, α _U1 : Passing through the center of gravity of the rotating member The smaller angle between the radial extension line and the line connecting the center of gravity of the rotating member to the inner end of the upper thrust dynamic pressure groove, α _U2 : The radial extension line passing through the center of gravity of the rotating member is the center of gravity and upper thrust dynamic pressure of the rotating member. L _TU : Radial length of upper thrust dynamic groove, T _L1 : Distance from center of gravity of rotating member to inner end of lower thrust dynamic groove, T _L2 : Rotation extending radially through the center of gravity of the rotating member: distance, _L1 α at the center of gravity of the member to the lower thrust dynamic pressure groove of the outer end The outer side of the center of gravity of the radial direction extension line passing through the center of gravity of the rotating member the rotating member and the lower thrust dynamic pressure groove: The inside end a small angle of each forming line connecting the center of gravity and the lower thrust dynamic pressure grooves of the rotary member, α _L2 L _TL is the radial length of the lower thrust dynamic pressure groove.

Meanwhile, the parameters related to the radial dynamic grooves 246 and 247 are the same as those described with reference to FIG. 6, and thus descriptions thereof are omitted.

In addition, in one embodiment of the present invention, the center of gravity G of the rotating member means a final state in which a disk, a clamp, or the like is mounted on the spindle motor. The spindle motor 200 shown in FIG. 9 is not mounted with a disc, a clamp, and the like, and the center of gravity G shown in FIGS. 10 to 11 means a center of gravity of a rotating member on which a disk, a clamp, and the like are mounted. do.

Referring to [Equation 2] to [Equation 6], it is possible to calculate the area for each item to calculate the [Equation 16].

Thus, by substituting the formula calculated in [Equation 2] to [Equation 6] in [Equation 16], it is the same as [Equation 17].

&Quot; (17) "

On the other hand, the center of gravity of the rotating member may be formed at various locations according to the structure and shape of the rotating member. In particular, in the case of the spindle motor 200 according to an embodiment of the present invention, if the center of gravity of the rotating member is formed in the upper radial dynamic groove or the lower radial dynamic groove area, the relation between the thrust dynamic groove and the radial dynamic groove is It can be established simply.

When the center of gravity (G) of the rotating member is located in the upper radial dynamic pressure groove area and the upper area thereof, the sleeve 240 is inclined at a portion where the upper radial dynamic pressure groove 248 is formed among the items of Equation (16). The area (S _U ) according to the difference between the gaps before and after the slope is negligibly small. Therefore, Equation 16 may be simplified to Equation 18 below.

&Quot; (18) "

In addition, when the center of gravity (G) of the rotating member is located in the lower radial dynamic pressure groove region and the lower region thereof, the sleeve 240 at a portion where the lower radial dynamic pressure groove 247 is formed among the items of Equation (16). The area S _L according to the difference between the gaps before and after the inclination is negligibly small. Therefore, Equation 16 may be simplified by Equation 19 below.

&Quot; (19) "

12A and 12B are schematic cross-sectional views of a disk drive apparatus using a spindle motor according to an embodiment of the present invention.

Referring to FIG. 12, the recording disk driving apparatus 800 in which the spindle motors 100 and 200 are mounted according to an embodiment of the present invention is a hard disk drive, and the spindle motors 100 and 200 and the head conveying unit ( 810 and housing 820. The thickness standard of the recording disk drive device 800 is 5 mm or less.

The spindle motors 100 and 200 have all the features of the spindle motor according to the present invention as described above, and may carry a recording disc 830.

The head transfer unit 810 may transfer the magnetic head 815 for detecting information of the recording disk 830 mounted on the spindle motor 100, 200 to the surface of the recording disk to be detected.

Here, the magnetic head 815 may be disposed on the support part 817 of the head transfer part 810.

The housing 820 covers a top of the motor mounting plate 822 and the motor mounting plate 822 to form an inner space for accommodating the spindle motor 100 and the head transfer part 810. 824.

The head transfer unit 810 is composed of a voice coil motor (VCM). However, when the power supply is suddenly interrupted in the voice coil motor, the magnetic head 815 may be located on the disk and the information recorded on the disk may be damaged.

In order to solve this problem, the recording disk driving apparatus 800 drives the voice coil motor by using the back electromotive force (B-EMF) of the spindle motor. The voice coil motor may be driven by the counter electromotive force to return the magnetic head 815 to an initial position, which is called emergency parking.

That is, when the power supply is stopped while the spindle motor is driven, electric energy is generated using the rotational force of the disk and supplied to the voice coil motor.

In the case of a 2.5 "disk, the back EMF (B-EMF) must be secured at least 0.35V / krpm so that the emergency parking of the head can be implemented. However, in the conventional disk drive device, the back electromotive force was not a problem, but the 2.5" type 5mm disk In the driving device, securing the counter electromotive force is a problem due to the limitation of the core height.

Therefore, it is necessary to design a long radial length of the core in order to secure the back electromotive force which is insufficient because the height of the core is lowered. However, since the 2.5 "disk has an inner diameter of 20 mm, there is a limit to the radial length of the core.

In this way, since a sufficient radial length of the core must be secured within the range of the inner diameter of the disc, the radial length of the sleeve in which the thrust bearing is formed by the radial length of the elongated core is also limited.

Therefore, it is important to design both the radial length of the core for securing the counter electromotive force and the radial length of the thrust bearing for securing the inclination rigidity.

100, 200: spindle motor
110: fluid dynamic bearing assembly
120: rotor
130: stator
210: Base member
220: Lower thrust member
230: shaft
240: Sleeve
250: Hub
260: upper thrust member
280: Magnet assembly
290: cap member

Claims (16)

A rotating member, and
A fixing member rotatably supporting the rotating member by fluid dynamic pressure,
An upper radial dynamic pressure groove and a lower radial dynamic pressure groove are formed on at least one of radially opposed surfaces of the rotating member and the fixed member;
A thrust dynamic pressure groove is formed on at least one surface of the rotating member and the surface facing in the axial direction.
Spindle motor satisfying the following [Equation 1].
[Formula 1]

Where T ₁ is the distance from the center of gravity of the rotating member to the inner end of the thrust dynamic pressure groove, T ₂ is the distance from the center of gravity of the thrust dynamic pressure groove to the outer end of the thrust dynamic pressure groove, α _{1 is the} center of gravity of the rotating member. Smaller angle of the angle between the radial extension line and the line connecting the center of gravity of the rotating member and the inner end of the thrust dynamic pressure groove, α ₂ : The radial extension line passing through the center of gravity of the rotating member is the center of gravity and thrust dynamic pressure groove L _T : The radial length of the thrust dynamic groove, R _U1 : Distance from the center of gravity of the rotating member to the lower end of the upper radial dynamic groove, R _U2 : of the rotating member Distance from center of gravity to upper end of upper radial dynamic groove, β _U1 : Radial extension line passing through center of gravity of rotating member is center of gravity of rotating member And the smaller angle of the angle formed by the line connecting the lower end of the upper radial dynamic groove, β _U2 : The radial extension line passing through the center of gravity of the rotating member forms the line connecting the center of gravity of the rotating member and the upper end of the upper radial dynamic groove. L _U : Axial length of the upper radial hydrodynamic groove, R _L1 : Distance from the center of gravity of the rotating member to the lower end of the lower radial dynamic groove, R _L2 : Lower radial dynamic groove from the center of gravity of the rotating member Distance to the upper end of, _L1 : The smallest angle between the radial extension line passing through the center of gravity of the rotating member and the line connecting the center of gravity of the rotating member to the lower end of the lower radial dynamic groove, β _L2 : of the rotating member The radial extension line passing through the center of gravity is the smaller of the angle formed by the line connecting the center of gravity of the rotating member to the upper end of the lower radial dynamic groove. Angle, L _L : Axial length of lower radial dynamic groove) The method of claim 1,
When the center of gravity of the rotating member is located above the lower end of the upper radial dynamic pressure groove in the axial direction, the spindle motor satisfies L _U in [Equation 1] as 0 and satisfies Equation 2 below. .
[Formula 2]

The method of claim 1,
When the center of gravity of the rotating member is located axially lower than the upper end of the lower radial dynamic pressure groove, the spindle motor satisfies L _L in [Equation 1] as 0 and satisfies Equation 3 below. .
[Equation 3]

The method of claim 1,
The rotating member includes a shaft, a hub extending radially outward from an upper end of the shaft, and a magnet and a disk mounted to the hub,
The fixing member includes a sleeve for rotatably supporting the shaft by fluid dynamic pressure, and a coil wound core disposed to face the magnet. 5. The method of claim 4,
The upper and lower radial dynamic pressure grooves are respectively formed on at least one of opposite surfaces of the shaft and the sleeve,
And the thrust dynamic pressure groove is formed on at least one of the opposite surfaces of the hub and the sleeve. The method of claim 5,
Between the shaft and the opposite surface of the sleeve there is formed a bearing gap filled with fluid,
The bearing gap is a spindle motor of 0.0005 ~ 0.002 times the diameter of the shaft. 5. The method of claim 4,
Spindle motors with back electromotive force (B-EMF) of 0.35 V / krpm or more when the power supply is interrupted. A spindle motor according to claim 4;
A magnetic head for recording and reproducing data of the disk; And
A head feeder for moving the magnetic head to a predetermined position on the disc,
Hard disk drive less than 5mm thick. A rotating member, and
A fixing member rotatably supporting the rotating member by fluid dynamic pressure,
An upper radial dynamic pressure groove and a lower radial dynamic pressure groove are formed on at least one of radially opposed surfaces of the rotating member and the fixed member;
An upper thrust dynamic pressure groove is formed on at least one surface of the upper side of the rotating member and the surface facing the axial direction of the fixing member, and on at least one surface of the lower side of the rotating member and the surface facing the axial direction of the fixing member. A lower thrust dynamic pressure groove is formed,
Spindle motor satisfying the following [Equation 4].
[Formula 4]

(T _U1 : distance from the center of gravity of the rotating member to the inner end of the upper thrust dynamic pressure groove, T _U2 : distance from the center of gravity of the rotating member to the outer end of the upper thrust dynamic pressure groove, α _U1 : weight of the rotating member A small angle between the radial extension line passing through the center and the line connecting the center of gravity of the rotating member to the inner end of the upper thrust dynamic groove, α _U2 : The radial extension line passing through the center of gravity of the rotating member L _TU : Radial length of upper thrust dynamic groove, T _L1 : Distance from the center of gravity of the rotating member to the inner end of the lower thrust dynamic groove, T _L2: distance from center of gravity of the rotating member to the lower thrust dynamic pressure outer end of the groove, α _L1: radial passing through the center of gravity of the rotating member Direction extension line of which forms the line connecting the inner end of the center of gravity and the lower thrust dynamic pressure grooves of the rotary member, each small angle, α _L2: the center of gravity of the radial direction extension line passing through the center of gravity of the rotating member the rotating member and the lower thrust dynamic pressure groove L _TL : Radial length of the lower thrust dynamic pressure groove, R _U1 : Distance from the center of gravity of the rotating member to the lower end of the upper radial dynamic groove, R _U2 : Rotating member Distance from the center of gravity of the upper radial dynamic groove to the upper end of the upper radial dynamic groove, β _U1 : The radial extension line passing through the center of gravity of the rotating member is the smaller of the angle between the line connecting the center of gravity of the rotating member and the lower end of the upper radial dynamic groove Angle, β _U2 : The radial extension line passing through the center of gravity of the rotating member is the center of gravity of the rotating member and L _U : Axial length of the upper radial dynamic groove, R _L1 : Distance from the center of gravity of the rotating member to the lower end of the lower radial dynamic groove, R _L2 : of the rotating member Distance from the center of gravity to the upper end of the lower radial dynamic groove, β _L1 : The smaller angle of the radial extension line passing through the center of gravity of the rotating member and the line connecting the center of gravity of the rotating member to the lower end of the lower radial dynamic groove , β _L2 : The smaller angle of the radial extension line passing through the center of gravity of the rotating member to the line connecting the center of gravity of the rotating member to the upper end of the lower radial dynamic groove, L _L : Axial length of the lower radial dynamic pressure groove) 10. The method of claim 9,
When the center of gravity of the rotating member is located axially higher than the lower end of the upper radial dynamic groove, the spindle motor satisfies L _U in [Equation 4] and satisfies Equation 5 below. .
[Formula 5]

10. The method of claim 9,
When the center of gravity of the rotating member is located axially lower than the upper end of the lower radial dynamic groove, the spindle motor satisfies L _L in [Equation 4] and satisfies Equation 6 below. .
[Equation 6]

10. The method of claim 9,
The rotating member includes a hollow sleeve, a hub extending radially outward of the sleeve, and a magnet and a disk mounted to the hub,
The fixing member includes a shaft inserted into the hollow of the sleeve to rotatably support the sleeve by fluid dynamic pressure, upper and lower thrust members extending radially outward of the shaft, and a coil disposed correspondingly to the magnet. Spindle motor with a wound core. The method of claim 12,
The upper and lower radial dynamic pressure grooves are respectively formed on at least one of opposite surfaces of the shaft and the sleeve,
And the upper thrust dynamic pressure groove is formed on at least one of the opposing surfaces of the upper thrust member and the sleeve, and the lower thrust dynamic pressure groove is formed on at least one of the opposing surfaces of the lower thrust member and the sleeve. The method of claim 13,
Between the shaft and the opposite surface of the sleeve is formed a bearing gap filled with fluid,
The bearing gap is a spindle motor of 0.0005 ~ 0.002 times the diameter of the shaft. The method of claim 12,
Spindle motors with back electromotive force (B-EMF) of 0.35 V / krpm or more when the power supply is interrupted. A spindle motor according to claim 12;
A magnetic head for recording and reproducing data of the disk; And
A head feeder for moving the magnetic head to a predetermined position on the disc,
Hard disk drive less than 5mm thick.

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